Ventilating shim for fan shaft bearings and the like



Jan. 5, 1954 A. B. NEWTON 2,665,059

VENTILATING SHIM FOR FAN SHAFT BEARINGS AND THE LIKE Filed Nov. 10, 1949 FEE 1t- 1-- gwuem/m ALVVIN B- NEWTON app W ATTORNEYS Patented Jan. 5, 1954 VENTILATING SHIM FOR FAN SHAFT BEARINGS AND THE LIKE Alwin B. Newton, Jackson, Mich., asslgnor to Acme Industries, Inc., Jackson, Mich., a. corporation of Delaware Application November 10, 1949, Serial No. 126,578

Claims. (01. 230211) This invention relates to ventilating devices used for bearings, and more particularly to a ventilating device which is used for a bearing in a stationary housing, the bearing supporting a rotating shaft.

The ventilating shim which is the subject of this invention has particular use with the shaft which supports a rotating fan in a relatively closed housing, the bearing requiring a lubricant and the housing being subjected by reason of the action of the fan, to air pressure which is less than atmospheric. Whereas, the ventilatin shim has particular use with this structure, it is recognized that there are many other uses for it.

In a fan housing subjected to lowered air pressure and in which a bearing housing and bearing are tightly seated against the fan housing, it is very common for condensation to seep from the inside of the fan housing into the bearing, resulting in the deterioration thereof. It is like- Wise very common for the grease in the bearing to migrate into the fan housing by reason of the lowered air pressure therewithin.

To solve the problems presented by such a situation, I have provided a shim adapted to be placed between the fan housing and the bearing housing, said shim being so formed as substantially to balance the air pressure on the outside and inside ends of the bearing, and also being so formed as to provide a current of air between its edge and the shaft so that any condensation which is within the fan housing will not tend to flow into the bearing.

Another advantage to be found in the ventilating shim is that it tends to keep the inner face of the bearing at a temperature approximating that of the outer face, by reason of the air flow across the inner face removing units of heat therefrom.

It is therefore, an object of this invention to provide a ventilating shim which will supply air to the inner side of a bearing.

A further object is to provide a ventilating shim which will prevent the migration of bearing lubricants from the bearing into the housing on which the bearing is mounted due to differential air pressure.

A further object is to provide a shim which will restrict the movement of condensation along the shaft from the housing into the bearing.

Further objects and advantages of my invention will be apparent from a consideration of the following specification and the appended claims 2 in connection with the accompanying drawings, in which:

Fig. I is a plan view of one form of a ventilating shim constructed according to my invention. and

Fig. II is a view in section along the line II--II of Fig. I, in which the ventilating shim is exaggerated in thickness for clarity and placed in its operative position between a shaft housing and a bearing housing.

The ventilating shim i0 is of sheet metal of any proper material and thickness, such as steel sheet in the order of Hi gauge, and is shown as substantially square in Fig. I. The shim Ii! may be of any desired outside shape. The shim ii] is provided with the required number of apertures 12 through which the fastening means I4 are used to hold the same in a desired position. The central aperture i6 is positioned as shown, and is of a size so that it has a relatively small clearance at the point I8 around the shaft iii, which it embraces.

The shim It! is also formed with a plurality of slots 2| which are open to the edge of the shim Ill. The particular shape of the slots 2! is not important, as long as it is open to the ambient atmosphere and extends towards the central aperture [6 a sufficient distance to insure its functioning in the manner desired.

In operation, the shim It] is mounted between the fan housing 22 and the bearing housing 2d. The fan housing 22 is formed with an aperture 26 through which the shaft 28 projects, and encloses a relatively restricted area which is subjected to lowered air pressure by reason of the action of the fan within the same. This decrease in air pressure is indicated as in the general area shown by the reference character 21.

The bearing housing 24 is attached by the means M to the fan housing 22, and houses the bearing 28 in supporting relationship to the shaft 20. The bearing housing 24 is formed with the extending flanges 30, the upstanding central boss 32, and a central aperture 34 in which the hearing 28 is situated. The lubricant is supplied to the bearing 28 through the fitting 36. The hearing housing 24 is formed with an annular internal cavity 38.

In position, as described above, and with the shaft 20 rotating and the fan 39 inducing a decreased air pressure in the area 21, air is allowed to pass through the area defined between the fan housing 22 and the bearing housing 24 in the slots 2|, to the central portion of the ventilating shim, and from there into the cavity 38. From 3 the cavity 38 the air is forced, by pressure diflerential, with increased velocity through the restricted opening 18 between the shaft 20 and the shim l0.

munication between the outside of said bearing housing and the inner annular cavity defined by said bearing housing.

3. In combination with a bearing housing hav- Wlth this COIlStIllCtiOIl, and with the fiOW of air 5 ing :a, bearin mounted therein an inner cavity as above described it will be apparent that the air pressure onthe internal end of the bearing 28 is substantiallyequal to the air pressureon the external end of the baring 28. This will predefined by said housing and positioned adjacent said bearingand a shaft supportedby said beari-ng; a ver'itil'ating shim forisaid housing for admitting ambient air thereto, said shim comprisvent the development of a sufiicient difierential ing a plate, means for mounting said plate on which would cause the lubricant to migrate from the bearing 28 along the shaft!!! into-the h'ousin 22.

iikewise, the movementuof .the airthroug-h the said bearing housing, an aperture defined by said plate and-positioned in substantially coaxial relation -wi th said bearing with the parts in the operative-position, and a plurality of slots defined slots 2| into the cavity 38 acts continually lidl5 by said plate,-said: slots extending for a distance the inner end of the bearing 28, thereby maintaining the same at a temperature closely approximating that of the outer -dge of' the' bearin 28. By providing the restricted opening-48 between the ventilating shim l0 and the shaft 2&,-the air is moved therethrough at sufficient velocity by" i'easonof the slight pressure" differential, which tends to keep all water vapor arid COI 1di1 SaItibnWithin"the fan nousingzz afld t0 prevent themoveiiient of the same into Contact with the-bearing 28.

Having desc'ribedinvention, what I"cl'aim as new" andde'sire 'toprotebtby Letters Patent is:

1. In combinatio'mwi'th a"fan and a'"fan' houswall, a rotatable shaft projecting 'through'said aperture, ab'earinghousing and bearing mounted ifig having" a, walr'ana ertureuefined' by Saidgreater-than the distance between the outer edge of said bearing housing and the edge of said inner "cavity"whei*eby" communication is afforded between the outside of said bearing housing and said inner cavity.

4. In combination with a-bearing-housinghiavinga' bearing. mounted therein an inner cavity Tdefinedby, said housing and positioned adjacent said-bearing and a shaft supported by said bearing, a ventilating shim for said housing for ad- .-mitting ambient air thereto, said shim comprising af'plate, an aperture. defined bytsaid plate in position for coaxial alignment with saidbearing, and -a"plurality of slots definedby' saidv plate, said slots extending'for a distance greater than the'dist'an'ce between the outer edge of said bearing -h'ous'ing and the edge of said inner cavity whereby communic'ation is afforded between-the "outside 'of said bearing housing and said inner bearing housing defining an internal"annular cavity.

"cavityadjac'ent said sha'ftf the provision 'of'ia ventilating shim'pomprising a plate, means for "mounting said platebetween s'a'id wall and's'aid bearing housing; a" central" ape'rture' defined by 5. As a new article ofmanufacture, a ventilatmg shim for. fan shaftsadapted to be inserted 'overthe shaft with. clearance between the shaft bearings'tructure and its supporting structure r adap m e id h ftwm "comprisinga plate; having a central aperture-to and aplurality oi "open-end ed slots defined by said plate, said slots b'eing'open to the'edge' of said plate and extending in a'dire'ction substantially toward the center'-of'--s'aid' platefor-adistance betweenthe edge of:-'said'-bearing housing and-the edge of -said cavity.

2. in combination with afanand'a fanhous- '-ing having a" wan; an aperture defined by said avail," a "rotatable shaft' projecting throughs'aid aperture, a bearing housing-and b'earingmounted on said wall in' juxtaposition tosaid aperture and in supporting relationship -to-saidshaft', said bearing housing deflning-an internal annular cavity adjacent to' said shaft, the provisionoi a ventilating- 'shimcomprising a plate; means for mountingsaid plate between said' wall"- and said bearing housing, a -central" aperture defined by said plate: andad'aptd to embrace said shaft,

and a plurality-of slots definedbysaidp'late and extending in a direction substantially-towardthe center of said plate and'of asize to afford comreceive the fan shaft with clearance, open ended slotsdefined' by' said plate, said slots-being open :to the outer edge of said plate-and extending inwardlytoward said aperture, and means defined 1n saidplate adjacent the outer edge thereof to re'ceiveshim locating structure.

I ALWIN B. NEWTON.

References Citedin the 'file 'of this patent STATES PATENTS Number 

